Abstract: The extracellular matrix (ECM) is a complex network of collagens, laminins, fibronectins and proteoglycans that provides a surface upon which cells can adhere, differentiate and proliferate. Defects in the ECM are the underlying cause of a wide spectrum of diseases. The ECM mediates endothelial cell polarity and under normal conditions can suppress pre-oncogenic transitions to a neoplastic state. We are constructing artificial, de novo collagen-based matrices using a hierarchic computational approach. These matrices will be physically characterized in the laboratory and used to probe the role of chemical and spatial organization in the ECM on the tumor forming potential of adhered cells. We are using a two-stage, computational strategy to construct an artificial ECM. A key technology is protCAD (protein Computer Automated Design), a software platform developed in our laboratory specifically for computational protein design. In the first stage, the sequences of short collagen-like modules are designed to independently assemble into trimers of programmed stability and specificity. These modules are then covalently connected using flexible peptide linkers to facilitate the selfassembly of controlled higher-order structures such as networks and fibrils. Encouraging experimental characterization of the first generation collagen designs suggests that our computational strategy is likely to succeed. Synthetic ECMs will be useful in biomedical research and translational applications. Mammalian cells will be grown on anisotropic, self-assembling nanostructured matrices to assay effects on cell polarity, cytoskeletal orientation and mophology. We will explore the ability of artificial matrices to suppress cell proliferation in the presence of various oncogenic signals. This will provide a powerful system for studying molecular aspects of the matrix biology of cancer. Successfully designed matrices will be applied to engineering safer artificial tissues. Public Health Relevance: The extracellular matrix is a complex network of proteins that provides a platform for cells to adhere on and assemble into complex tissues. Defects in the extracellular matrix are linked to a number of bowel, bone and skin diseases, autoimmune disorders such as Lupus and a broad range of cancers. Artificial, nano-scale matrices will help us study the role of the matrix in disease, and provide safe biomaterials for tissue engineering.